The Chennai-based company had sold 2,36,751 units in the same month last year.
"The company lost sales of 20,000 vehicles owing to non-availability of trucks due to transporters' strike," TVS Motor Company said in a statement.
Total two-wheeler sales for the month stood at 2,21,002 units as against 2,27,589 in September 2014, it added.
Motorcycle sales declined 1.36 per cent to 90,378 units last month as against 91,627 a year ago.
Scooter sales grew 14 per cent to 75,369 units in September 2015 as against 65,993 in the same month last year.